Gas lift valve



Oct. 19, 1965 c. R. cANALlzo GAS LIFT VALVE 3 Sheets-Sheet 1 Filed Oct. ll. 1962 INVENTOR Carlos R. Gonolizo BY l d@ ATTORNEYS www mm. um

Oct. 19, 1965 c. R. cANALlzo 3,212,517

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Oct. 19, 1965 c. R. cANALlzo GAS LIFT VALVE 5 Sheets-Sheet 5 Filed Oct. 11, 1962 United States Patent O 3,212,517 GAS LIFT VALVE Carlos R. Canalizo, Dallas, Tex., assignor to Otis Engineering Corporation, Dallas, Tex., a corporation of Delaware Filed Oct. 11, 1962, Ser. No. 229,837 16 Claims. (Cl. 137-155) This invention relates to well tools, and more particularly to air or gas lift valves for use in oil wells and the like for controlling admission of gas or air to a column of fluid in the well to lift the column and aid in flowing the fluid from the well.

In conventional gas lift systems, the well equipment usually includes a string of relatively small pipe called the tubing which is inserted inside a larger diameter pipe called the casing The liquids produced by the well flow to the surface through the tubing and the gas or air is introduced under controlled pressures and volumes into the annular space or annulus between the tubing and the casing and injected through suitable gas lift valves into the tubing to aid in lifting the column of well fluids or oil inside the tubing to the surface. It is desirable that such gas lift valves be of such structure that the bore of the tubing is not decreased at the locations where the gas lift valves are connected to the tubing in order to permit the passage of Well tools through such gas lift valves and that additionally the external diameter of such valves be as small as possible in order to permit passage of tools through the annulus during washover operations of the well and the like. It is further desirable that the operation of the gas lift valve be controlled by the pressure conditions either within the annulus at the location of .the gas lift valve or the pressure conditions within the tubing at the gas lift valve.

Accordingly, an object of this invention is to provide a new and improved gas lift valve, connectable in a string of tubing to form a section thereof, having a centra longitudinal passage or bore of a diameter not smaller than the bore of the tubing.

Another object is to provide a gas lift valve having a relatively small outside diameter.

Still another object is to provide a gas lift valve of concentric construction connectable in a string of tubing to form a section thereof and having an internal longitudinal passage whose diameter is not smaller than the drift diameter of the tubing and an annular ow passage disposed concentrically about the longitudinal passage, the valve having ports communicating the flow passage with the interior of the tubing and the exterior thereof, valve means being disposed in such flow passage which are responsive either to the pressure within the tubing or the pressure exteriorly of the tubing and which controls flow of gas from the exterior of the tubing into the tubing.

A further object is to provide a gas lift valve which includes an anular valve member longitudinally movable about a mandrel connectable in a tubing string to form a section thereof, wherein the mandrel and the annular valve member are provided with coengageable annular seat surfaces, one of the seat surfaces being beveled and the other being arcuate whereby the valve is self aligning.

A still further object is -to provide a gas 4lift valve wherein the annular valve member is moved to open position by an annular piston movable by the force of the fluid pressure in the annulus and admitted lthereto by an auxiliary or pilot valve.

Still another object is to provide a gas lift valve wherein the effective orifice of the valve means is of relatively large dimensions in order to permit introduction of gas into the tubing at a relatively great rate when the gas lift valve is open.

ICC

A further object is to provide a gas lift valve responsive to the pressure either within the tubing or within the annulus which opens at a higher value of the pressure to which it is responsive than the value of such pressure at which it closes.

A still further object is to provide a gas lift valve whose valve means opens and closes with a snap action whereby throttling of the gas flow through the valve, and consequent flow cutting of the valve means seat surfaces, is prevented.

Another object of the invention is to provide a gas lift valve wherein the operative components of the gas lift valve are not exposed either to the interior or the exterior of the tubing in order to prevent damage by Well tools, high pressures, flow cutting, erosion or other such forces.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURE l is a view partly in section and partly in elevation of the upper portion of a gas lift valve embodying the invention;

FIGURE 2 is a View similar to FIGURE l being a continuation thereof and showing the lower portion of the gas lift valve;

FIGURE 3 is a perspective view of the annular piston of the valve illustrated in FIGURES 1 and 2;

FIGURE 3A is a fragmentary sectional view of a modified form of the pilot valve means of the gas lift valve illustrated in FIGURES l and 2;

FIGURE 4 is a view, partly in elevation and partly in section, of the upper portion of a modified form of the valve;

FIGURE 5 is a continuation of FIGURE 4 and is a view, partly in elevation and partly in section, of the lower portion of the valve illustrated in FIGURE 4;

FIGURE 6 is a fragmentary sectional View of another modied form of the valve;

FIGURE 7 is a view, partly in elevation and partly in section, of the upper portion of another modied form of the valve;

FIGURE 8 is a continuation of FIGURE 7 and is a view partly in elevation and partly in section of the lower portion of the valve;

FIGURE 9 is a perspective view of the annular valve member of the valve illustrated in FIGURES 7 and 8; and

FIGURE 10 is a fragmentary sectional view of another modified form of the valve.

Referring now particularly to FIGURES 1, 2 and 3 of the drawing, the gas lift valve 10 embodying the invention includes an elongate tubular mandrel 11 whose opposite end portions 12 and 13 are externally threaded whereby the mandrel 11 may be connected between and t-o adjacent sections of tubing by means of the usual couplings or collars, not shown, whereby the mandrel forms a section of the string of tubing. The internal diameter of the bore or longitudinal passage 15 of the mandrel is at least as great as the internal or drift diameter of the tubing. An outer sleeve 16 which includes a lower cap 17, an intermediate tubular sleeve section 18 and an upper cap 19 is disposed about the mandrel intermediate its ends.

The annular lower cap 17 is secured to the mandrel by a lock wire 22 which may be inserted into the aligned external and internal grooves 23 and 24 of .the mandrel and the lower cap 17, respectively, through a slot 26 of the lower cap. An O-ring 27 is disposed in an internal annular recess of the lower cap to seal between the lower cap and the mandrel. The lower end of the intermediate sleeve section 18 telescopes over the upper reduced portion 28 of the lower cap and is rigidly secured .thereto in any suitable manner, as by the weld 29. The upper end portion of the sleeve section 18 telescopes over the reduced portion 30 of the upper cap 19. The downwardly facing annular shoulder 31 of the upper cap engages the upper end of the tubing sleeve section 18. The upper cap has an external annular recess in which is disposed an O-ring 33 or other suitable sealing means for sealing between the upper cap and .the sleeve section 18. The upper cap is rigidly secured to the mandrel by a set screw 34 threaded in a lateral bore 35 of the upper cap. The upper cap has an internal annular recess in which is disposed an O-ring 36 or other suitable sealing means which seals between the cap and the mandrel.

The longitudinal bore of the upper cap is enlarged, as at 38, to receive the upper end portion of a tubular member 39 whose upper end is rigidly secured to the top cap in any suitable manner, as by the weld 40'. The upper portion of the tubular member 39 is provided with a longitudinal groove 42 whose lower end communicates with the annular pressure chamber 44 defined by the external surface of the tubular member 39 and .the internal surface of the lower reduced section 30 of the upper cap below the downwardly facing shoulder 46 thereof. A compressible fluid, such as air, may be introduced into the pressure chamber 44 through the lateral port 48 of the upper cap which is closable by the plug 49 threaded in .the enlarged outer portion of the port 48. A suitable gasket 50 may be interposed between the inner end of the plug and the shoulder 51 of the top cap to seal therebetween.

The lower `end of the pressure chamber opens into an annular bellows 55 disposed about the mandrel. The bellows includes an inner annular section 56 whose upper end is secured yto the inner tubular member 39 in liuid tight relation thereto by any suitable means such as silver solder and whose lower end is similarly secured in fluid tight relationship to the upper end of an annular pilot valve ring 58.

The outer annular section 60 of the bellows 55 similarly has its upper end secured to the lower end of the annular reduced extension 30 of the upper cap and its lower end secured to the pilot valve ring 58. It will be apparent that the two bellows sections 56 and 60 with the valve ring 58 define an annular upwardly opening chamber which opens into the annular .pressure chamber 44. The pilot valve ring is provided with at least one ball valve 64 rigidly secured to its lower end surface in any suitable manner, as by silver solder, which is engageable with the annular seat 65 of the port ring 66 for closing the port 67 thereof. The port ring 66 extends about the external annular flange 68 of the mandrel 11 and is rigidly secured thereto in any suitable manner, as by welding or silver solder. An O-ring 70 or other suitable sealing means is disposed in an external annular recess of the ange 68 of the mandrel to seal between the port ring and the mandrel. Similarly, the port ring is provided with an external annular recess in which is disposed an O-ring 72 or other suitable sealing means for sealing between the port ring and the internal surface of the sleeve section 18.

The pilot or 'ball valve 64 controls flow of uid from the exterior of the sleeve section 18 through .the ports 75 thereof into the annular bellows chamber 76 below the lower end of the upper cap and above the port ring and thence to the annular piston chamber 77 disposed below the port ring 66. An annular piston 78 slidably disposed in the piston chamber is engageable with the lower end surfaces or shoulders 79 of the upper ends of the upwardly extending collet fingers 80 of the annular valve member 82. The annular valve member 82 controls the fiow of lifting gas from the inlet ports 84 of the sleeve section 18 through the annular fiow passage 85 formed by the sleeve section and into the longitudinal 4 passage 15 of the mandrel through the discharge ports 86 of the mandrel.

The annular valve member 82 has an annular arcuate upwardly facing seat surface 88 engageable with the downwardly facing upwardly and outwardly extending beveled or frusto-conical seat surface 89 of the mandrel provided by the external annual fiange 90 thereof and disposed below the outlet ports 86 thereof. The engagement of the seat surfaces of the mandrel and the valve member limits upward movement of the valve member on the mandrel. Downward movement of the annular valve member in the flow passage is limited by the engagement of the downwardly facing shoulders 93 of the external bosses at the upper ends of the collet lingers 80 with the upwardly facing annular shoulder 96 of the sleeve section 18. The annular valve member 82 is provided with an external annular recess in which is disposed an O-ring 97 or other suitable sealing means which seals between the valve member and the cylindrical inner surface of the sleeve section 18.

It will be apparent that when the annular valve member is moved downwardly by the piston 78 to a lower position wherein the shoulders 93 of the collet fingers engage the shoulder 96 of the sleeve section, the inlet ports 84 of the sleeve are placed in communication with the discharge or outlet ports 86 of the mandrel through the flow passage 85 so that gas may iiow through the annular iioW passage 85 past the now spaced seat surfaces 88 and 89 of the annular valve member and of the mandrel, respectively, which define an annular orifice. It will be noted that the effective orifice of the fiow passage when the valve mernber is in its open position is quite large since it is annular in configuration and extends about the mandrel.

The provision of the concentric seat surfaces 88 and 89 of the annular valve member and the mandrel causes the valve to be self aligning and, since the seat surface 88 of the valve member is curved while the seat surface 89 of the mandrel is beveled downwardly and inwardly, the valve member moves in the liow passage until the curved seat surface 88 of the annular valve member makes line contact with a portion of the beveled or frusto-conical seat surface 89 of the mandrel. The O-ring or resilient seal means 97 of course engages the cylindrical inner wall surface of the sleeve section 18 and thus the seal effected by the O-ring 97 is never broken.

An annular resilient check valve 100 is disposed in the iiow passage 85 to prevent reserve iiow of fluids from the longitudinal passage of the mandrel 11 to the exterior of the sleeve section. The annular check valve has an inner fiange 102 received in the external recess 103 of the mandrel 11 and its outer surface engages the internal surface of the sleeve section to prevent its outward displacement. The check valve has a tapered upper lip portion 106 which extends past the inlet ports or slots 84 and engages the internal surface of the sleeve section to close the ports against fiow of fluids from the flow passage 85 through the ports 84. The lip portion 186 of course flexes resiliently to permit liow of fluids through the inlet ports 84 into the passage 85.

The piston 78 is tubular in form and is cut at an angle or scarfed, as at 110, so that it may easily pass such obstructions as the external flange of the mandrel during the installation of the piston on the mandrel. In addition, the cutting or scarfing of the piston permits the fiow or leak of iiuid past the adjoining surfaces 111 and 112 of the ring formed by such cut for a purpose to be described below. The piston 78 is preferably made of a plastic such as Teflon or Delrin having a low coefficient of friction. The piston of course sealingly engages the mandrel and the sleeve section.

The components of the gas lift valve are assembled by first rigidly securing the port ring 66 to the mandrel, installing the piston 78 by sliding it upwardly over the lower end of the mandrel to the position illustrated in FIGURE 2, telescoping the annular valve member upwardly over the lower end of the mandrel to the position illustrated in FIGURE 1, and then passing the check valve 100 over the lower end of the mandrel and thence upwardly until its internal flange 102 is received in the external recess 103 of the mandrel.

The assembly of the lower cap and the sleeve section 18 is then moved upwardly over the lower end of the mandrel 11 to the position illustrated in FIGURE 2 wherein the grooves 23 and 24 of the lower cap and the mandrel are aligned whereupon the lock wire 22 is inserted into the two aligned grooves through the radially and circumferentially extending slot 26 of the lower cap. The tubular member 39, the bellows 55, and the valve ring 58 and the ball or pilot valve 64 are then installed in place as an assembly by sliding the assembly downwardly over the upper end of the mandrel which is then secured in place by the set screw 34. The pressure chamber 44 is filled with a compressible gas, such as air, through the inlet port 48 which is closed by the plug 49 and gasket 50. The mandrel 11 is connected between adjacent ends of adjacent sections of tubing and is lowered with the tubing into the well through the well casing thereof.

The force of the charge of gas in the pressure chamber 44 acting on the bellows 55 now holds the pilot valve 64 i in its lower position in engagement with the seat 65 of the port ring 66 closing the port 67. In installations where the operation of gas lift valve is to be controlled by the pressure within the annulus of the well between the string of tubing and the casing, the well is provided with the usual intermitting device which causes lifting gas to be injected into the well casing at relatively great rates for short periods of time at regularly spaced intervals of time. When the intermitting device causes the injection of lifting gas into the annulus, the pressure within the annulus rises and when the pressure exceeds a predetermined value sufficiently great to overcome the force exerted on the bellows by the charge of compressible gas in the pressure chamber 44, the pressure of the lifting gas is communicated to the bellows chamber 76 through the port 75 of the sleeve section and exerts a force on the bellows which tends to cause the bellows to contract and lift the valve ring and the pilot valve 64 upwardly to open the port 67 of the port ring.

The fluid pressure from the annulus acts across the effective area of the bellows less the area of the pilot valve 64 sealed by the engagement of the pilot valve with the seat 65. This area of the pilot valve is exposed to the fluid pressure from within the flow passage 15 of the mandrel 11 since discharge ports 86 of the mandrel communicate with the flow passage 85 above the external flange 90 of the mandrel and since the scarf or cut 110 in the piston provides fluid communication between opposite ends of the piston 78. Since this area of the ball valve exposed to the fluid pressure from within the flow passage 15 is much smaller than the area of the bellows exposed to the fluid pressure from the annulus and since the pressure within the mandrel is not as great as the pressure within the annulus, the pressure within the tubing string cannot cause opening movement of the pilot valve.

When the pressure of the lifting gas within the annulus attains a predetermined value, which acting on the bellows overcomes the force applied to the bellows 'by the charge of compressed gas within the pressure chamber 44, the valve member moves upwardly causing the pilot valve to move out of engagement with the seat 65 to open the port 67. When the pilot valve moves out of sealing engagement with the seat 65, the fluid pressure within the annulus acts not only across the bellows but also across the area of the pilot valve previously sealed by its engagement with the seat 65 so that the fluid pressure from Within the annulus now acts across a greater area of the bellows and therefore with a greater force to move and to hold the pilot valve in its upper open position. When the port 67 is opened, the fluid pressure of the lifting gas from the annulus communi-cated to the piston chamber 77 above the piston 78 exerts a force on the piston tending to move it downwardly. Since the effective area of the piston now exposed to the fluid pressure from the annulus is greater than the annular area of the valve member between the internal surface lof the intermediate sleeve section 18 engaged by the O-ring 97 and the line of sealing engagement of the arcuate seat surface y88 of the annular valve member with the beveled seat surface 89 of the mandrel 11 exposed to such pressure whose force applied upwardly to this area tends to move the valve member upwardly and hold it in closed position, and since the fluid pressure within the longitudinal passage of the mandrel whose force tends to move the piston upwardly is substantially less than the annulus pressure, the piston 78 is moved downwardly in the piston chamber and moves the valve member downwardly to open position. Lifting gas now flows inwardly into the annular flow passage of the gas lift valve through the ports 84, the check valve flexing resiliently inwardly to permit such inward flow, and then flows through the discharge ports 86 of the mandrel into the longitudinal flow passage 15 to aid in lifting a column of well liquids in the string of tubing to the surface. The well liquids of course flow upwardly into the string of tubing through the lower open end of the tail pipe secured to the mandrel 11 to form the column of well liquids which is to be lifted to the surface.

The effective orifice of the cut or scarf 110 of the piston is quite small compared to the combined orifice or area of the discharge ports 86 of the mandrel and the pressure differential thus created across opposite ends of the piston tends to hold the piston in its lower position wherein it holds the valve member in its lower open position. The combined orifice or area of the discharge ports 86 of the mandrel is also greater than the effective orifice or annular area between spaced seat surfaces 88 and 89 of the annular valve member and the mandrel, respectively, so that a pressure differential is created across the annular valve member which tends to move it upwardly toward closed position but the force of the pressure differential acting on the annular valve member is smaller than the force of the pressure differential to which the piston 78 is subjected so that the piston holds the valve member in open position as long as the pilot valve 64 is -in its upper open position. f

The lifting gas flows into the tubing 15 and -moves the column or slug of liquids upwardly in the string of tubing to the surface. The effective orifice 4or area between the seating surfaces 88 and 89 of the annular valve member and of the mandrel is relatively large so that lifting gas flows from the annulus between the string of tubing and the well casing at a substantial rate into the string of tubing to cause the column of well liquids in the string of tubing above the discharge ports 86 to be lifted to the surface of the well and discharged from the upper end of the string of tubing.

When the intermitting device arrests or stops further injection of the lifting gas into the annulus at the end of a predetermined period of time, the pressure within the annulus falls as the lifting gas continues to flow from the annulus into the longitudinal passage of the mandrel. When the pressure within the annulus drops to a second predetermined value, which is lower than the value thereof at which the pilot valve moved to open position, the for-ce of the charge of compressed gas within `the pressure chamber 44 acting through the 'bellows 55 exceeds the force applied to the bellows by the pressure of the lifting gas in the annulus tending to hold the pilot valve in open position and moves the pilot valve 64 downwardly into engagement with the seat 65 of the port ring to close the port 67. Since a greater area of the bellows and the ball valve is exposed to the pressure of the fluid in the annulus when the pilot valve is in its upper position than when the ball valve is in its lower closed position, the predetermined value of the pressure within the annulus at which the pressure of the charge of compressed gas within the pressure chamber 44 is elective to move the pilot valve back to its closed position is lower than the predetermined value of the pressure which is required to move the pilot valve to its open position. As a result, the pilot valve will move to its open position at a predetermined value of the pressure of the lifting gas within the -annulus which is higher than the value of such pressure at which it is moved to its closed position.

When the pilot valve is moved to its closed position in sealing engagement with the seat 65 closing the port 67, the pressures at opposite ends of the piston 78 equalize since the cut or scarf 110 provides a restricted orice for the iiow of iiuid between the opposite ends of the piston. As the pressure differential across the piston 78 is thus equalized, the pressure differential across the annular valve member, which increases rapidly as the pressure within the string of tubing above the ports 86 drops as the column or slug of liquids is discharged lfrom the upper end of the string of tubing at the surface, is effective to move the annular valve member and the piston 78 upwardly and cause the arcuate seat 8S of the valve member to engage the seat 89 of the mandrel to close the liow passage 85 to stop further flow of lifting gas into the longitudinal passage of the mandrel 11 and thus into the tubing string.

The gas lift valve now remains in its closed position until the intermitting device again causes injection of lifting gas into the annulus and the above sequence of operation of the gas lift valve is repeated to aid in lifting another column of well liquids which have accumulated in the tubing string above the discharge ports 86 to the surface.

The area of the pilot valve 64 exposed to the pressure from the longitudinal passage 15 of the mandrel 11 when the pilot valve is seated in sealing engagement with its seat 65 is very small compared to the area of the bellows exposed to the pressure of the lifting gas in the annulus so that the gas -lift valve operates primarily in response to the pressure conditions within the annulus and its operation is controlled by controlling the pressure conditions within the annulus by means of an intermitting device or the like.

In well installations where the operation of the gas lift valve is to be responsive primarily to the pressure conditions within the string of tubing at the discharge ports 86 of the mandrel 11 in order that lifting gas be introduced by a gas lift valve into the string of tubing whenever the column of well liquids in the string of tubing attains a predetermined height above the discharge ports 86, the gas lift valve is made more responsive -to the pressure within the string of tubing at the discharge ports 86 by increasing the area of the pilot Valve 64 exposed to the pressure at the discharge ports when the pilot valve is seated on the seat 65. This may be accomplished by increasing the diameter of the annular line contact of lthe pilot valve 64 with its seat 65 or, as illustrated in FIGURE 3A, by providing the port ring with several .ports 67, instead of just one, and the pilot valve ring 58 with a corresponding number of ball valves which close the ports 67 by engagement with the seat 65 thereof. The combined area of the valves 64 exposed to and acted on by the fluid pressure of the discharge ports 86 is thus quite great and the pilot valve ring will be moved upwardly toward open position by the force of this pressure acting on -the valves 64 when the pressure within the string of tubing at the discharge port increases to a predetermined value, as when the column of well liquids in the string of tubing above the discharge ports 86 reaches a predetermined height for a given predetermined pressure within the annulus.

In such well installations, the lifting gas is injected into the annulus between the string of tubing and the well casing through a relatively small bore choke and a regulator which stops injection of the gas into the 'annulus whenever the pressure within the annulus attains a predetermined value. The choke permits injection of the lifting gas into the annulus at a much lower rate than the rate at which the gas lift valve permits the lifting gas to enter into the string of tubing when the gas lift valve is open. Accordingly, when the gas lift valve in such installations is open, the lifting gas is discharged into the string of tubing from the annulus through the gas lift valve at a much yfaster rate than the lifting gas is being injected into the annulus through the choke and therefore the pressure within the annulus drops whenever the gas lift valve opens. The regulator does not permit the pressure within the annulus to rise to the degree necessary to open the pilot valve unless a column of well liquids of predetermined height above the discharge ports 86 is present in the string of tubing. The pressure of the lifting gas acting on the bellows tends to move the pilot valve to open position. When such column of well liquids rises to a predetermined height above the discharge ports 86, the bellows and the force of the pressure within the string of tubing at the ports 86 overcomes the force exerted by the charge of compressed gas in the pressure chamber 44, the pilot valve opens, the piston 78 moves the annular valve member to its open position and lifting gas ows into the string of tubing to aid in lifting the column of well liquids to the sur-face. Since the lifting gas ilows from the annulus into the tubing string through the gas lift valve at a greater rate than the rate at which the choke permits injection of lifting gas into the annulus, the pressure within the annulus decreases as soon as the gas lift valve opens and when it decreases to a predetermined value lower than the value at which the pilot valve opened, the charge of compressed gas in the pressure chamber 44 causes the pilot valve 64 to close. The an* nular valve member is moved upwardly to its upper closed position when the column of liquids is discharged at the surface of the well and the pressure within the tubing at the discharge ports consequently decreases. The regulator now again permits flow of fluid into the annulus through the choke until the annulus pressure attains the predetermined value at which the regulator closes. The gas lift valve then remains closed until the column of well liquids in the string of tubing above the discharge ports 86 again attains the predetermined height to cause again the movement of the pilot valve to its upper open position. This cycle of operation of the gas lift valve, wherein the gas lift valve opens and closes in response to the pressure within the string of tubing at the gas lift valve, will continue automatically as long as the gas is injected into the annulus and well liquids continue to flow into the string of tubing through the open lower end of the tail pipe secured to the mandrel 11 of the gas lift valve. It will be apparent that the pressure of the lifting gas in the annulus acting on the bellows 55 also affects the operation of the gas lift valve. This is desirable since no purpose would be served if the gas lift valve opened when the pressure of the lifting gas was substantially equal to or lower than the pressure in the string of tubing at the discharge ports 86. The check valve in this case would of course prevent flow of well liquids into the annulus through the ports 84 of the outer sleeve. The bore of the choke, the setting of the regulator, and the pressure of the charge of compressed gas in the pressure chamber are predetermined in accordance with the conditions of each well to ensure that, in normal operation, the pressure of the lifting gas in the annulus will attain the .predetermined value to cause the regulator to stop injection of lifting gas into the well before the column of well liquids in the string of tubing attains the predetermined height at which the gas lift valve will open.

It will now be seen that the ratio of the area sealed by the pilot valve, which may comprise one or more ball valves, when in engagement with its seat or seats of the port ring, relative to the effective area of the bel- 9 lows exposed to the pressure rfrom the annulus may be varied by varying the number of ports 67 of the port ring and the number of ball valves as well as by varying the diameter of the seat 65 and diameter of the ball valve in order to Vary the desired difference between the value of the pressure to which it is responsive at which the pilot valve opens and the value of such pressure at which it closes.

It will -further be seen that since the ports 75 of the outer sleeve section 18 communicating with the bellows chamber 76 and the ports 67 are of relatively large combined orifice, the rate of tiow of lifting gas into the piston chamber 77 is relatively great so that the piston 78 and the annular valve member 82. move rapidly to open the gas lift valve whenever the pilot valve 64 is open. In addition, since the leakage of fluid through the cut or scarf 110 between the surfaces 111 and 112 of the piston ring 78 is not minute, the annular valve member moves back to its closed position quickly once the pilot valve 64 is closed as the pressures at opposite ends of the piston 78 quickly equalize. While the illustrated and described annular piston which moves the annular valve member to open position has the cut or scarf 110 provided -to facilitate installation or assembly `of the piston on the mandrel which also provides a restricted oriiice for ow of iluid across opposite annular ends of the piston, it will be apparent that if the annular piston were a solid ring, a port extending through the piston parallel to the central axis thereof would be provided to permit such equalization of pressure across the piston to permit its upward movement. The orifice of such piston port would of course be much smaller than the combined orifice of the ports 75 of the outer sleeve 16.

It will now be seen that the annular valve member is moved quickly between its fully open and fully closed positions so that throttling of the ow of fluids between the seat surfaces 88 and 89 of the annular valve member land of the mandrel 1'1 is minimized preventing ow cutting or erosion of the seat sur-faces by the high velocity flow therepast of fluids which may carry abrasive particles.

It will further be apparent that .the operation of the gas lift valve may be made responsive primarily to the pressure within the annulus between the string of tubing and the well casing or that the operation of the -gas lift valve may be responsive to the pressure within the string of tubing at the gas lift valve.

It will further be seen that the gas lift valve whose mandrel, connectable in a string of tubing to form a section thereof, has a longitudinal passage whose diameter is not smaller than the diameter of the tubing and that due to the concentric construction of the gas lift valve, the outside diameter of the gas lift valve is held to aminimum.

It will further be seen that the provision of the annular valve member 82 permits the gas lift valve to have a large effective orifice whereby the lifting gas may pass through the gas lift valve at relatively great rates into the string of tubing when the gas lift valve is open.

It will further be seen that the operative elements of the gas lift valve are disposed concentrically between the exterior of the mandrel and the outer sleeve -16 and are therefore not exposed either to the interior or the exterior of the tubing and thus protected against damage by objects or iluids passing or flowing through the tubing -or through the annulus.

The gas lift valve 150 illustrated in FIGURES 4 and 5 is substantially similar in structure and mode of operation to the gas lift valve illustrated in FIGURES 1, 2 and 3, and, accordingly, elements of the gas lift valve 150 have been provided with the same reference numerals to which the subscript a has been added as the corresponding elements of the lift valve 10.

The port flange or ring 66a of the mandrel 11a of the gas lift valve 150 may be integral with the mandrel and have a reduced external annular portion 152 over which telescopes the upper end of the sleeve section 18a of the outer sleeve 16a. The port ring has an external annular recess in which is disposed an O-ring 153 or other suitable sealing means for sealing between the upper end of the sleeve section and the port ring. The lower end of the outer sleeve section 18a is rigidly secured to the lower cap 17a by the weld 29a. The cap 17a is secured to the mandrel in the same manner as the lower cap 17 of the gas lift valve 10 and the check valve 100a is similarly secured between the mandrel 11a and the outer sleeve 16a to prevent reverse ow of fluids through the inlet ports 84a ofthe outer sleeve.

The annular valve member 82a is identical in structure and function to the annular valve member l82 of the gas lift valve 10 and has an external annular recess in which is disposed an O-ring 97a which seals between the annular valve member and the internal surface of the sleeve section 18a above the ports 84a and is also provided with an internal annular flange which provides the arcuate upwardly facing seat surface 88a which is engageable with the upwardly and outwardly beveled or frusto-conical seat surface 89a provided by the external annular flange 90a of the mandrel.

The annular valve member is moved to its open position by the piston 78a slidably disposed in the annular piston chamber 77a formed by the sleeve section 18a and the mandrel 11a below the port ring of the mandrel. The piston 7 8a is identical to the piston 78 and is cut or scarfed in the same'manner to facilitate its installation on the mandrel and to provide a restricted orifice between the upper and lower ends thereof.

The pilot valve 64a for controlling flow of tiuid -frorn the annulus into the annular piston chamber 77 is of elongated rod-shaped contiguration having an arcuate seat surface 155a at its lower end which is engageable with the arcuate seat 65a of the port ring `66a of the mandrel to close the port 67a thereof. The pilot valve 64a extends through the passage 156 of the bellows housing 157 whose reduced lower end is threaded in the upwardly opening bore 159 of the port ring 66a above the lateral port 75a of the port ring. The outer end of the lateral port 75a communicates with the exterior of the gas lift valve and its inner end communicates with the lower end of the passage 156 of the bellows housing 157.

The enlarged upper tubular portion 161 of the bellows housing provides an elongate bellows chamber 162 in which is disposed the bellows 165 to whose lower end the pilot valve 64a is secured in any suitable manner, as by silver solder, brazing, or the like. The upper end of the bellows 165 is connected to the tting 167 having a reduced portion which telescopes into the upper end of the bellows housing and is rigidly secured therein by any suitable means as by welding. The fitting 167 may be of the usual ty-pe having an inlet port closed by a suitable plug 168 by means of which the bellows may be lled with a charge of compressed gas so that the charge of compressed gas in the bellows biases the pilot valve 64a towards closed position in engagement with the seat 65a of the port 67a.

The mandrel 11a has an external longitudinal recess 170 above the port ring 66a in which are received longitudinal portions of the bellows housing 157 in order that the housing not protrude outwardly of the outer sleeve 16a.

The gas lift valve functions in the same manner as the gas lift valve 10 to control admission of lifting gas from the annulus between a well casing and the string of tubing in which the mandrel 11a is connected and constitutes a section thereof. The bellows is lled with a charge of compressed gas which biases the pilot valve 64a toward closed position in engagement with the seat 65a closing the port 67a. The annular valve member 82a is held in its upper closed position preventing flow of lifting gas from the annulus into the longitudinal passage `a of the mandrel through the ports 84a of the outer sleeve, the annular liow passage 85 between the outer sleeve and the mandrel and the discharge ports 86a of the mandrel by the pressure differential existing thereacross until the intermitting device at the surface causes injection of the lifting gas into the annulus and increases the pressure within the annulus at the gas lift valve to a predetermined value which is suliiciently great that the force of this pressure acting on the bellows 165 through the port 75a and the passage 156 overcomes the force of the charge of compressed gas within the bellows 165 and causes the bellows to contract. The pressure from the annulus is then communicated to the upper end of the piston chamber 77a through the port 75a, the passage 156 and the port 67a. The piston 78a is moved downwardly by the `force of the fluid pressure from the annulus and moves the annular valve member downwardly to its open position whereupon the lifting gas flows into the longitudinal passage 15a of the mandrel 11a and thus into the string of tubing to lift the column of well liquids in the string of tubing above the discharge ports 86a of the mandrel lla. When the intermitting device closes, it stops injection of lifting gas into the annulus and the pressure in the annulus drops to a second predetermined value, which is lower than the value at which the pilot valve 64a was moved to its upper position since when the pilot valve moves towards open position the area thereof previously sealed by its engagement with the seat 65a is exposed to the pressure of the fluids in the annulus. When the pressure in the annulus drops to the lower second predetermined value, the pilot valve moves to its closed position and, since the pressure across the upper and lower opposite ends of the piston 78a equalizes due to the provision of the cut or scarf lilla in the piston 78a, the pressure differential across the annular valve member, which exists due to the fact that the combined orifice or area of the ports 86a is greater than the area or effective orifice between the valve member and the mandrel when the valve member is in its lower open position, moves the valve member and the piston upwardly to closed position wherein the arcuate seat surface 88a of the annular valve member engages the frustoconical seat surface 89a of the external ange 90a of the mandrel 11a.

It will be apparent that since the area of the pilot valve 64a exposed to the pressure within the longitudinal passage 15a of the mandrel and defined by the line of sealing engagement of the arcuate seat surface 155 of the pilot valve with the seat 65a is very small, the operation of the pilot valve is primarily responsive to and is controlled by the pressure conditions within the annulus. The difference or spread between the value of the pressure at which the pilot valve opens and the value at which it closes may of course be varied by varying the area of the pilot valve which is exposed to the pressure within the mandrel when the pilot valve is in closed position by varying the diameter and curvature of the seating surfaces 155a and 65a of the pilot valve and of the port ring.

The gas lift valve 200 illustrated in FIGURE 6 is similar to the valve 150 and accordingly the elements of the valve 200 have been provided with the same reference numerals to which the subscript b has been added as the corresponding elements of the valve 150.

The gas lift valve 200 has a pilot valve 64b whose operation is responsive primarily to the pressure conditions within the string of tubing and is employed in such well installations as that described above wherein the well is provided with a choke which controls the rate of injection of lifting gas into the annulus of the Well and a regulator which stops the injection of lifting gas into the annulus when the pressure within the annulus attains a predetermined value. The annular port ring or flange 66b of the mandrel 11b has a lower reduced annular external portion 152b over which telescopes the upper end of the sleeve section 18b of the outer sleeve 16h. The reduced portion 152b is provide with an external annular recess in which is disposed an -O-ring l153b which seals between the port ring or ange and the sleeve section.

The port ring has an upwardly extending extension 262 over which telescope the lower end of the bellows housing 157b secured thereto in fluid tight engagement therewith in any suitable manner, as by silver solder, welding or the like. The mandrel 11b has a longitudinally extending groove or recess 170b in which the inner portions of the bellows housing are received.

The bellows 165b disposed in the bellows housing has a spider 204 secured to its lower end in any suitable manner, as by welding, provided with the ports 205 which communicate with the port 67h of the external mandrel port llange 66b. The bellows 165b is filled with a charge of compressed gas which yieldably biases the pilot valve 64b, secured to the upper end of the bellows 16517, into closed seating engagement with the seat 207 of the bellows housing closure 208 to close the port or passage 209 thereof. The housing closure has a reduced lower portion 210 which telescopes into the upper end of the bellows housing and is rigidly secured thereto in iiuid tight engagement therewith in any suitable manner, as by welding, silver solder or the like.

The area of the pilot valve 64b exposed to the pressure within the annulus between the well casing and the string of tubing in which the mandrel 11b of the valve 200 is connected to form a section thereof is smaller than the effective area of the bellows 165b exposed to the pressure in the longitudinal passage 15b of the mandrel 11b so that the pilot valve will remain in closed position until the pressure in the longitudinal passage 15b of the mandrel increases, due to the column of Well liquids in the string of tubing increasing to a predetermined height above the discharge ports 86h. For example, if the area of the pilot valve 64b exposed to the pressure of the annulus when the pilot valve is in closed position is about eighty percent of the effective area of the bellows 16512, if the bellows is charged With a compressed gas to a pressure of 500 pounds per square inch, and if the regulator is set to stop injection of the lifting gas into the annulus when the pressure within the annulus reaches 505 pounds per square inch, the pilot valve will remain in its upper closed position until the height of the column of Well liquids in the string of tubing attains a height which increases the pressure in the piston chamber 77b, since the piston chamber 77b is in communication with the discharge ports 86h through the restricted orifice provided by the cut or scarf 110b of the piston 78b, to 480 pounds per square inch. The force of the pressure from the annulus acting on the bellows in conjunction with the downward force applied to the pilot valve 64b by the pressure within the annulus then causes the bellows to contract and moves the pilot valve 64b to open position. The pressure of the fluid within the annulus is then communicated to the piston chamber 77b above the piston 78b and causes downward movement of the piston which in turn causes downward movement of the annular valve member 821; to open position. The valve member 82h will then remain in open position permitting liow of lifting gas from the annulus through the inlet ports 84h, the annular flow passage b of the valve 200 and the discharge ports 86a of the mandrel into the string of tubing. When the pressure within the annulus drops due to the fact that the lifting gas flows at a greater rate into the string of tubing through the gas lift valve than the rate at which the lifting gas is injected into the well through the choke and regulator, the pilot valve will move back to its upper position when the pressure in the annulus drops to a second predetermined value. This second predetermined value is lower than the value of the pressure in the annulus which causes opening of the pilot valve since once the pilot valve opens the bellows is exposed to the pressure from the annulus. When the pilot valve closes, the pressure differential across the valve member 82a is effective to move the valve member back to its upper closed position since the pressure across the upper and lower ends of the piston 7 8b equalizes due to the restricted orifice provided by the cut or scarf 110b.

It will now be apparent that this difference or spread in the values of the pressure within the annulus which cause the pilot valve to open and to close may be varied by varying the ratio of the area of the pilot valve 64b exposed to the pressure within the annulus when the pilot valve 64b is in closed position and the effective area of the bellows 165b. It will be apparent therefore that the operation of the gas lift valve is responsive not only to the pressure within the tubing string at the valve but also to the pressure within the annulus, it being apparent that if the regulator is set to permit the casing pressure to increase to a higher value, the value of the pressure within the tubing which will cause opening of the pilot valve, and therefore the height of the column of well liquids above the ports 86a, will decrease and, conversely if the regulator is set to prevent the pressure in the annulus to exceed a lower value, a higher value of the pressure in the string of tubing at the ports 86a and consequently, a higher column of well liquids above the ports 86a, is required to open the pilot valve. Since the pressure in the annulus is controlled by the regulator, the valve is in effect made to operate or be responsive to the pressure in the string of tubing at the discharge ports 86b of the valve.

The gas lift valve 250 illustrated in FIGURES 7 and 8 is also similar in construction and mode of operation to the gas lift valve 10 illustrated in FIGURES l and 2 and accordingly the elements of the valve 250 have been provided with the same reference numerals to which the subscript c has been added as the corresponding elements of the gas lift valve 10.

The outer sleeve 16C of the gas lift valve 250 includes a lower cap 17c and the sleeve section 18e which is provided with the inlet ports 84C which open into the annular ow passage 85C between the outer sleeve and the mandrel 11C. The upper end portion of the sleeve section telescopes over the reduced intermediate portion 252 of the upper cap 19C which is rigidly secured at its upper end to the mandrel 11al in any suitable manner, as by the weld 254. The intermediate portion of the cap 19C has an external annular recess in which is disposed an O-ring 255 which seals between the sleeve section 18C and the intermediate portion 252. The lower portion 257 of the upper cap is reduced below the intermediate portion 252 thereof, and the upper end portion of the pilot valve 260, which is in the form of a flexible tubular sleeve or element, is disposed between the reduced lower portion of the upper cap and the upper portion of the sleeve section 18C above the slots or ports 262 of the sleeve section. The upper portion of the sleeve sealingly engages the lower portion of the upper cap 19e and is held against movement relative thereto by its frictional and compressional engagement with the lower portion and the internal surface of the sleeve section 18C. If desired, the lower portion of the upper cap may be provided with external spaced annular flanges 263 to further engage and hold the upper end of the pilot valve against displacement. The annular support member has an internal flange 267 telescoped over the external annular flange 268 of the mandrel 11C. The adjoining annular surfaces of the two flanges are provided with aligned annular grooves in which is receivable, through a suitable radially outwardly opening circumferentially extending slot, not shown, of the support member, a lock wire 270 which holds the support member against movement relative to the mandrel 11C. The lower annular end portion of the pilot valve 260 extends between the mandrel and the support member above the flanges 267 and 268 and sealingly engages the adjacent surfaces thereof. The lower end portion of the pilot valve is held against movement relative to the mandrel and the support member by frictional and compressional forces and, if desired, the support member may be provided with spaced internal flanges 271 which further hold the lower portion of the pilot sleeve 272 against displacement.

It will be lapparent that the upper and lower portions of the pilot valve may be secured to the lower portion 257 of the upper cap and to the mandrel, respectively, by suitable adhesive or bonding agents, if desired.

The support member 266 has a plurality of external longitudinally extending slots 273 providing communication between the inlet ports 262 and the annular piston chamber 77C when the resilient pilot valve is moved inwardly out of engagement with the internal surfaces of the sleeve section 18e to open the ports 262. An intermediate portion of the tubular pilot valve 260 is adapted to extend across the slots or ports 262 and sealingly engage the internal surface of the sleeve section 18C to close the ports 262 and prevent flow of fluid from the exterior of the sleeve to the piston chamber 77c through the passages formed by the external slots 273 of the support member.

The intermediate portion of the pilot valve is yieldingly urged or biased toward position closing the ports 262 by a charge of compressed gas in the pressure chamber 275 formed by the internal annular recess 277 of the upper cap 19C. The pressure chamber 275 communicates with the annular chamber 278 between the intermediate portion of the pilot valve and the exterior of the mandrel 11e` below the lower end of the upper cap through one or more of the longitudinally extending internal grooves 279 of the upper cap below the recess 277 thereof. The pressure chamber 275 may be lilled with a charge of compressed gas through a lateral filler port 282 of the upper cap whose upper portion is enlarged and threaded to receive the plug 283 which with the gasket 284 closes the filler port.

The collet ngers 80e of the annular valve member 82e are provided with external bosses 290 which are receivable in the annular internal recess 292 of the sleeve section 18C. The collet bosses provide lower shoulders 293 which extend perpendicularly relative to the longitudinal axis of the annular valve member and are engageable with the lower upwardly facing annular shoulder 295 dening the lower end of the internal annular recess 292 to limit downward movement of the annular valve member. The upper beveled shoulders 297 of the external bosses 290 of the collet fingers extend downwardly and outwardly and are engageable with the similarly downwardly and outwardly inclined beveled upper shoulder 298 of the sleeve section 18e` which denes the upper end of the internal recess 292. The collet fingers, when in the position illustrated in FIGURE 8 wherein the bosses engage the internal surface of the sleeve section above the recess 292, are held in retracted position by the engagement of the outer surfaces of the bosses with the internal surface of the sleeve section. The collet fingers move resiliently outwardly when permitted to do so upon the movement of the valve member to its lower open position as the bosses move into alignment with the boss recess of the sleeve section. The inherent position of the collet ngers is such that the collet ngers must be forced inwardly against the resistance offered by the resilient metal of which they are formed to assume the inner retracted position illustrated in FIGURE 8. It will be apparent that upward movement of the annular valve member from its lower open position is resisted by the engagement of the upper boss shoulders 297 with the upper annular shoulder 293 defining the upper end of the boss recess and the resilience of the collet fingers. Since these shoulders are beveled, when a suicient upward force is exerted on the annular valve member, the camming engagement of these beveled shoulders of the bosses and of the boss recess moves the upper ends of the collet fingers inwardly against the resistance offered the collet fingers against such inward flexing to permit such upward movement of the valve member to closed position,

The gas lift Valve 250 is especially adapted for use in well installations wherein it is desired that the injection of the lifting gas into the tubing string from the annulus between the tubing string and the well casing be controlled by or be responsive to the pressure conditions within the annulus. The gas lift valve 250 is connected in a tubing string to constitute a section thereof in the usual manner by connecting the externally threaded upper portion 12C of its mandrel 1'1c to a section of tubing and connecting the lower externally threaded portion 13C thereof to the usual tail pipe which also constitutes a section of the tubing. The pressure chamber 275 is filled with a predetermined charge of compressed gas through the filler port 282 which is then closed by the gasket 284 and the plug 283, The charge yof compressed gas in the chamber 275 then biases the tubular resilient pilot valve lou-twardly into engagement with the internal surface of the sleeve section 18e so that the pilot valve closes the ports 262. The well fluids flow up through the open lower end of the tail pipe through the string of tubing to form a column -above the discharge ports 86C. The lifting gas is injected into the annulus of the well between the well casing and the tubing string under the control of an intermitting device which causes injection of the lifting gas at a relatively great rate for short peri-ods of time a-t regularly spaced intervals in the usual well known manner. When the pressure in the annulus increases as the gas is injected into the annulus to the value at which the force exerted thereby -on the intermediate portion of the pilot valve 260 through the slots 262 exceeds the force exerted on the pilot valve by the charge of compressed gas in the pressure chamber 275, the resilient tubular pilot valve flexes inwardly and permits tiow of the lifting gas into the upper end of the piston chamber 77c through the longi-tudinal grooves 273 of the supporting member 266. Trie force of such fluid pressure applied to the upper annular end surface of the piston 78C now causes downward movement of the piston and, since the lower end of the piston 78C is in engagement with the upper ends of the collet finge-rs 80C of the annular valve member, the valve member is moved downwardly to open position. The sliding engagement of the bosses 290 with the internal lsurface of the sleeve section `18C above the boss recess 292 thereof permits such downward movement of the annular valve member until the bosses 290 I move into `alignment with the internal boss recess 292 of the sleeve Isection whereupon the colle-t fingers spring resiliently outwardly to position the bosses in the boss recess. The engagement of the abrupt downwardly facing shoulders 293 of the collet bosses with the upwardly facing abrupt shoulder 295 of the sleeve section now arrests further downward movement of the annular valve member. When the valve member moves downwardly, its Seat surface 88C moves out of engagement with the beveled seat surface 89C provided by the internal annular ange 90C of the mandrel and the lifting gas now ows through the inlet ports 84C of the outer sleeve 16C into the passage 85C and thence through the discharge por-ts 86C of the mandrel into the tubing string to aidin lifting the column or slug` of well liquids present in the tubing string above the ports 86C 'to the surface of the well. When the intermitting device stops injection of the lifting gas at the end of the predetermined short period of time, the pressure within the annulus drops rapidly since the lifting gas continues to flow out of the annulus into lthe tubing string through the open gas lift valve. As the pressure in the annulus drops below the predetermined value at which the pilot .valve opened, the force of the charge of compressed gas in the chamber 27S becomes effective to again move the pilot valve to position closing the ports 262 so that the pressure from the annulus is no longer communicated to the upper end of the piston chamber 77C and the piston 78e is now free to move back to its upper position since the pressure on opposite upper and lower ends of the piston 78C may now equalize through the orifice provided by lthe cut or scarf 11100. If the collet fingers and the sleeve section are not provided with the detent bosses 290, the pressure differential across the valve member would cause the valve member 88C to move upwardly to closed position as soon as the pilot valve moved back to its closed position so that the gas lift valve would close at substantially the same value of the pressure in the annulus as the value thereof at which it is moved to open position. Since'the collet iingers 80e inherently resiliently resist inward movement thereof which is necessary to move the bosses 290 out of the boss recess 292 to permit upward movement of the annular valve member to its upper closed position, the annular valve member will not move to its upper closed position immediately upon closing of the pilot valve but will remain in its lower position until the pressure differential thereacross increases due to the lowering of the pressure within the string of tu-bing as the column or `slug of well liquids is discharged from the tubing string. As this pressure differential increases, the upward force exerted on the annular valve member increases until it is sufficiently great to cause the collet iingers to be resiliently exed inwardly due to the camming engagement of the beveled shoulders 297 and 298 of the bosses and of the sleeve section, respectively, to release the valve member for movement to its upper closed position. ll`he annular valve member thus moves to its closed position. The gas lift valve then remains closed for a predetermined interval of time during which the intermitting device prevents ow of lifting gas into the annulus and during which the well iiuids again flow upwardly into the string of tubing to form a column of well liquids above the discharge ports 36C. When the intermitting device again opens, the above sequence of operation is repeated to cause another slug or column of well liquids to be lifted to the surface through the tubing string.

The difference or spread between the value of the pressure in the annulus at which the gas lift valve opens and the Value thereof at which the gas lift valve closes may be varied by varying the resilience or stiffness of the collet fingers as by making the valve member of different substances or by varying their thickness, or by varying the angle or inclination of the camming shoulders or surfaces 297 and 298 or the areas of such camming surfaces.

The gas lift valve 300 illustrated in FIGURE 10 is similar in structure and function to the gas lift Valve illustrated in FIGURES 1 and 2 and accordingly elements of the gas lift valve 300 have been provided with the same reference numerals to which the subscript d has been added as the corresponding elements of the gas lift valve 10.

l The annular valve member 82d of the gas lift valve 300 is mounted on the mandrel 11d thereof for limited longitudinal movement thereon and its collet fingers 80d are provided with internal bosses 94d whose shoulders 93d are engageable with the annular upwardly facing shoulder 302 of the mandrel 11d to limit downward movement of the annular valve member towards open position. The annular Valve member is provided with an external annular flange having an upwardly facing arcuate seat surface 88d which is engageable with the upwardly and inwardly beveled or frusto-conical seat surface 304 of the -sleeve section 18d provided by the internal annular flange 305 thereof. Upward movement of the annular valve member is limited by the engagement of the annular seat surfaces 88 and 304 of the annular valve member and of the outer sleeve. The discharge ports 86d of the mandrel are located between the spaced collet fingers 80d of the annular valve member 82d so that the collet lingers do not interfere with the liow of charge ports 86d when the annular valve member is moved to its open position by the piston 78d. The annular valve member has an internal annular recess in which is disposed an O-ring 308 or other suitable sealing means for sealing between the annular valve member and the mandrel.

It will be apparent that the gas lift valve 300 functions in exactly the same manner as the gas lift valve to control flow of lifting gas into the longitudinal ow pas sage d of the mandrel 11d to aid in lifting well liquids in the string of tubing of which the mandrel 11d constitutes a section and that the gas lift Valve 300 differs from the gas lift valve 10 in having the valve member slidably mounted on the mandrel instead of in the outer sleeve and in that the outer sleeve is provided with an internal flange which provides the seat surface engaged by the arcuate seat surface of the annular valve member.

It will also be apparent that if desired the annular valve member and the mandrel 11d may be provided with the same type of coengageable detent means as the bosses 290 and the boss recess 298 of the valve member and the outer sleeve section of the gas lift valve 250 in the event that a large difference or spread is desired between the val-ue of the pressure to which the gas lift valve 300 is responsive at which the yannular valve member is moved to open posit-ion and the value of such pressure at which it moves to closed position. v It will be apparent that the difference or spreads between the value of the pressure to which the gas lift valves 10, 150 and 250 are made responsive, at which these valves open and the values thereof at which these valves close may also be predetermined or controlled by providing the collet fingers of the annular valve members thereof with external bosses, such as the bosses 290 of the collet ngers of the annular valve member of the gas lift valve 250, and the sleeve sections of their outer sleeves with annular internal boss recesses such as the boss recess 292 of the sleeve section 18e of the outer sleeve 16C of the gas lift valve 250.

It will further be seen that the pilot valve of each of the gas lift valves is biased towards closed position by such means as a charge of compressed gas acting on a bellows and that other biasing means may be provided for this purpose. For example, the pilot valve 64 of the valve 10 could be biased toward closed position by a compression spring disposed between the inner and outer bellows sections 56 and 60 with its lower end engaging the valve ring 58 and its upper end engaging any suitable means of the valve, such as an external downwardly facing annular end surface of the lower end of the upper cap 19. The charge of gas of the bellows of the pilot valve 64a similarly could be replaced by a compression spring disposed in the bellows whose lower end would bear against theA upper end of the valve 64a and whose upper end would bear against the litting 167. Similarly, the charge of compressed gas in the bellows 165b could be replaced by a compression spring whose lower end would bear against the spider 204 and whose upper end would bear against the upper end of the valve 64b. In some well installations where variations inthe temperature conditions in the well would greatly affect the ranges of the pressure at which the pilot valve operated if the biasing means were a charge of compressed gas, the springs whose operation is not appreciably influenced by temperature changes may be employed.

It will now be seen that each of the gas lift valves embodying the invention illustrated and described includes a tubular member such as the mandrel 11 having means disposed thereon, such as the outer sleeve 16, which provide an annular flow passage about the tubular member having inlet ports communicating the annular ow passage with the exterior of the valve and with discharge ports which communicate the bypass ow passage with the interior of the tubular member.

It will further be seen that a valve means is disposed in such annular ow passage to close the flow passage against flow of fluids from the exterior of the valve to the interior thereof and that the valve means and the tubular member have an arcuate annular seat surface and a beveled annular seat surface, respectively, which engage to close the flow passage when the valve means is moved in one direction longitudinally of the tubular member and which are spaced from one another to provide an annular orifice smaller than the effective combined orice 0f the discharge ports of the tubular member whereby the annular valve member is biased towards closed position -by the pressure differential existing thereacross when the valve is open and uid ows through the llow passage Ifrom the inlet ports to the discharge ports.

It will further -be seen that each of the gas lift Valves illustrated and described includes an annular piston disposed about the tubular member and engageable with the annular valve member for moving the annular valve member to open position.

It will -further be apparent that in each of the illustrated and described forms of the gas lift valve the operation of the valve member moving means is controlled by a means responsive to the pressure conditions either within the tubular member or externally thereof and that the piston is moved by the fluid pressure from the exterior of the tubular member when such uid pressure is applied to one end of the piston.

It will further =be seen that the application of the uid pressure to the piston is controlled by a pilot valve having means for biasing it toward position preventing application of the fluid pressure from the exterior of the tubular member to the piston and responsive to the pressure either within the tubular member or the exterior thereof t0 open a port to permit application of the uid pressure from the exterior of the tubular member to the piston upon the occurrence of a predetermined pressure condition either interiorly or exteriorly of the tubular member and movable to closed position upon the occurrence of another presssure condition exteriorly of the tubular member.

It will further be seen that in each of the illustrated and described forms of the gas lift valve the piston is slidable in an annular chamber provided by the Outer sleeve and the mandrel and-having port means closable by a pilot valve for admitting iluid from the exterior of the mandrel to the piston chamber to move the valve member to open position.

It will further be seen that the annular piston is provided with a restricted orice, as by the cut or scarf 110, in order both to facilitate installation of the piston ring on the mandrel and also to provide for the equalization of pressures across the piston when the pilot valve means is closed and thus permit movement of the annular valve member and the piston to the positions assumed thereby when the annular valve member is in upper closed position.

It will Ifurther be seen that the pilot valve has operator means, such as the bellows of the valve 10 having an area exposed to the pressure from the exterior of the gas lift valve when the pilot valve is in closed position and means such as the area of the ball valve or pilot valve exposed to the pressure within the mandrel when the pilot valve is in closed position and to the pressure vfrom the exterior of the valve when the pilot valve is inlopen position so that by the provision of appropriate ratios between these areas, the opening and closing of the pilot valve, and therefore the opening and the closing of the gas lift Valve, may be made responsive to the pressure conditions either within the interior of the tubular member or mandrel or the exterior of the gas lift valve, and the valve may be made to close at a lower predetermined value of the fluid pressure to which it is responsive than the predetermined value thereof at which it opens.

It will further be seen that the difference or spread between the values of the pressure to which the valves are responsive at which the valves open and close may be increased and varied by providing the annular valve member with detent means, such as the resilient collet ngers provided with bosses receivable in a recess of the outer sleeve, for releasably restraining the valve member in its open position.

It will also be apparent that the bellows 55 and the chamber 44 of the gas lift valve 10, the bellows 165 of the Vgas lift valve 150 and the Ibellows 165b of the gas lift valve 200 may be partially filled with a non-compressible liquid and partially with a compressible fluid so that the bellows may contract to the extent necessary to open the ports closed by the valves which are movable by the bellows and so that further contraction of the bellows is then prevented 'by the non-compressible liquid in order that the bellows not be crushed 'by abnormally high pressures which exist in the well when it is loaded with mud or water.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A valve including: a tubular member having an internal flow passage; means on said tubular member providing an annular flow passage about said tubular member closed at its ends, said tubular member having a discharge port communicating said internal flow passage with said annular flow passage, said means having an inlet port spaced longitudinally of said valve from said discharge port and communicating said annular flow passage with the exterior of said valve; an annular valve seat on one of said tubular member and said means on said tubular member in said flow passage between said ports; annular valve means movably mounted on said tubular member coating with said seat for closing said flow passage between said inlet and discharge ports, said valve means when in open position being disposed between said inlet and discharge ports and movable toward said discharge port toward closed position engaging said seat, said valve means when in open position providing with said valve seat and with one of said tubular member and said means on said tubular member an annular orifice in said flow passage about said tubular member located between said inlet and discharge ports, said discharge port having a greater effective orice than said annular orifice whereby when said valve means is in open position and uid is flowing from said inlet port through said annular ow passage and said discharge port to said internal ow passage a pressure differential is created across said valve means tending to move said valve means to position closing said annular flow passage; annular operator piston means in said flow passage between said discharge port and the adjacent closed end of said passage operatively associated with said valve means and exposed at one end to fluid pressure in said passage between said valve seat and said discharge port and at its opposite end to fluid pressure in said passage between said piston means and said closed end of said passage; and conduit and control means for conducting fluid pressure from exteriorly of said Valve to said passage between said piston and said closed end of said passage to act on said opposite end of said piston to move said piston and said valve means associated therewith to move said valve means out of engagement with said seat to open the annular passage for flow, said operator piston means having a greater cross-sectional area than the effective cross-sectional area of said annular valve means.

2. A valve including: a tubular member having an internal flow passage; means on said tubular member providing an annular flow passage about said tubular member, said tubular member having discharge port means communicating said internal flow passage with said annular passage, said means on said tubular member having inlet port means communicating said annular flow passage with the exterior of said valve, said inlet and discharge port means being longitudinally spaced and located adjacent opposite ends of said annular ow passage; annular seat means intermediate said port means extending radially into said annular ow passage from one of said tubular member and said means on said tubular member and providing an annular restriction intermediate the ends of said annular flow passage; an annular valve member in said annular flow passage movable in said annular passage in the direction of flow from the inlet to the discharge port means to engage said seat means and close said flow passage between said inlet and discharge port means, said valve member when in open position and said one of said tubular member and said means on said tubular member providing an annular orifice between said inlet and said discharge means and about said tubular member, said discharge port means having a greater effective orifice than said annular orifice whereby when said valve member is in open position and uid is flowing through said inlet port means through said annular passage and said discharge port means to said internal flow passage, a pressure differential is created across said valve member tending to move said valve member toward said seat means, said means on said tubular member and said tubular member providing an annular piston chamber disposed about said tubular member; and an annular piston being engageable with the valve member disposed in said piston chamber slidably engaging said tubular member and said means on said tubular member for moving said valve member in one direction out of engagement with said seat means to open position, said annular piston having a greater cross-sectional area than the cross-sectional area of said annular restriction, said valve having means for supplying uid pressure to the chamber and for exhausting fluid pressure from said piston chamber.

3. The Valve of claim 2, wherein said last mentioned means includes means providing a flow passage communicating said piston chamber with the exterior of said valve whereby fluid from the exterior of the valve may move said piston in said one direction; and pilot valve means for closing said flow passage communicating with said piston chamber and responsive to the pressure from one of said internal flow passage and the exterior of said valve for controlling ow of fluid from the exterior of the valve to said piston chamber.

4. The valve of claim 3 wherein said piston has means providing communication between opposite ends of said piston whereby pressures across said piston may be equalized when said pilot valve means closes said flow passage communicating with said piston chamber to permit movement of said piston and said valve member in a direction opposite said one direction.

5. The valve of claim 3 wherein said pilot valve means has an effective area exposed to the pressure from the exterior of said valve when said pilot valve means is open which is greater than the effective area exposed thereto when said pilot valve means is closed whereby said pilot valve means remains in open position until the pressure from the exterior of the valve drops below the value thereof at which said pilot valve means moves from position closing said flow passage.

6. The valve of claim 3 and means biasing said pilot valve means to position closing said flow passage communicating with said piston chamber.

7. The valve of claim 3 wherein said pilot valve: means has means exposed and responsive to the pressure lfrom one of said internal ow passage and the exterior of said valve for moving said pilot valve means to position opening said flow passage when said pressure from-y one of said internal flow passage and the exterior of said valve increases to a predetermined value, said valve hav-A ing a pressure chamber containing a charge of compressible gas, said last mentioned means being exposed tg 21 the pressure of said charge of compressed gas whereby said pilot valve means is biased by said charge toward position closing said flow passage communicating with said piston chamber.

8. The valve of claim 7, and restraining means for releasably restraining said valve member against movement from open position toward closed position, said restraining means including an internal recess provided in said means on said tubular member and resilient means carried b-y said valve member and having boss means receivable in said internal recess when said valve means is in open position, said resilient means biasing said boss means into said recess, said boss means and said means carried by said tubular member having coengageable means for moving said boss means out of said recess against the force exerted by said resilient means upon movement of said valve member toward closed position.

9. A gas lift valve including: a mandrel having a longitudinal ow passage and connectable in a string of tubing to form a section thereof; an outer sleeve mounted on said mandrel providing an annular space extending about and longitudinally of said mandrel to provide an annular flow passage and an annular piston chamber, said mandrel having a discharge port com-municating said longitudinal flow passage of said mandrel with said annular flow passage, said outer sleeve having an inlet port communicating the exterior of said valve with said annular flow passage; an annular valve member slidably mounted in said annular flow passage between said inlet and outlet ports for limited longitudinal movement between said inlet and discharge ports relative to said mandrel, said mandrel having annular seat means intermediate said ports extending radially outwardly into said annular flow passage and providing an annular restriction intermediate the ends of said annular flow passage, said seat means and said valve member having co-engageable annular seat surfaces for closing said flow passage, said valve member being movable in said annular passage in the direction of flow from the inlet port to the discharge port to cause said seat surfaces to engage and close said flow passage, said outer sleeve closing one end of said annular flow passage; an annular piston slidably mounted in said piston chamber and closing the other end of said annular ilow passage, said piston being engageable with said annular valve member -for moving said valve member in one direction longitudinally of the main mandrel to open position wherein said co-engageable seat surfaces are spaced from one another to provide an annular orifice, said discharge port having a greater eiective orifice than said annular orifice whereby when said valve member is in open position and fluid is flowing through said inlet port, said annular passage and said discharge port to said longitudinal flow passage, a pressure differential is created across said valve member tending to move said valve member in the direction of flow from said inlet port to said discharge port, said annular piston having a greater cross-sectional area than the cross-sectional area of said annular restriction, said valve having means providing a ow passage communicating said piston chamber with the exterior of said outer sleeve; and pilot valve means carried by said mandrel responsive to the pressure within one of said longitudinal flow passage of the mandrel and the exterior of said outer sleeve for opening said passage communicating with said piston chamber to permit flow of fluid from the exterior of said outer sleeve into said piston chamber to move said piston in said one direction, said piston having a restricted orifice communicating said piston chamber With said annular flow passage, said outer sleeve and said mandrel providing an annular bellows chamber; an annular bellows connected to said pilot valve means and disposed in said annular bellows chamber and about said mandrel; and means on said mandrel providing an annular pressure chamber extending about said mandrel and communicating with the interior of said annular bellows for biasing said pilot valve means 22 to closed position, said outer sleeve having port means communicating the exterior of said outer sleeve with said bellows chamber whereby said bellows moves said pilot valve means to open position when the pressure exteriorly of said valve increases to a predetermined value.

10. The gas lift valve of claim 9, and a no-n-compressible liquid in said -bellows limiting contraction of said bellows.

11. A .gas lift valve including: a mandrel having a longitudinal ow passage and connectable in a string of tubing to form a section thereof; an outer sleeve mounted on said mandrel providing an annular space extending about and longitudinally of said mandrel to provide an annular flow passage and an annular piston chamber, said mandrel having a discharge port communicating said longitudinal flow passage of said mandrel with said annular flow passage, said outer sleeve having an inlet port communicating the exterior of said valve with said annular flow passage, said inlet and discharge ports being longitudinally spaced; an annular valve member slidably mounted in said annular ow passage for limited longitudinal movement between said inlet and outlet ports and relative to said mandrel, said mandrel having annular seat means intermediate said inlet and discharge port means extending radially outwardly into said annular flow passage and providing an annular restriction intermediate the ends of said annular flow passage, said seat means and said valve member having co-engageable annular seat surfaces for closing said flow passage, said valve member being movable in said annular passage in the direction of flow from the inlet port to the discharge port to cause said seat surfaces to engage and close said ow passage between said inlet and discharge ports, said outer sleeve closing one end of said annular flow passage; an annular piston slidably mounted in said piston cha-rnber and closing the other end of said annular passage, sai-d piston -being engageable with said annular valve member for moving said valve member in one direction longitudinally of the main mandrel to open position wherein said co-engageable seat surfaces are spaced from one another to provide an annular orifice, said discharge port having a greater effective orice than said annular orifice whereby when said valve member is in open position and fluid is flowing through said inlet port, said annular passage and said discharge port to said longitudinal passage, a pressure differential is created across the valve member tending to move said valve member in the direction of flow from said inlet port to said discharge port, said annular piston having a greater crosssectional area than the cross-sectional area of said annular restriction, said valve having means providing a ow passage communicating said piston chamber with the exterior of said outer sleeve; and pilot valve means carried by said mandrel responsive tothe pressure within one of said longitudinal ow passage of the mandrel and the exterior of said outer sleeve for opening said passage communicating with said piston chamber to permit flow of fluid from the exterior of said outer sleeve into said piston chamber to move said piston in said one direction, said piston having a restricted orifice communicating said piston chamber with said annular flow passage; means secured to said mandrel providing a bellows chamber; a bellows connected to said pilot valve means mounted in said bellows chamber, and means biasing said pilot valve means toward closed position, said bellows being exposed to the pressure from said annular iiow passage through said orifice of said piston whereby said pilot valve means is moved to open position by said bellows when said bellows is contracted when the pressure within the longitudinal ow passage of said mandrel increases to a predetermined value.

12. The gas lift valve of claim 11, and a non-compressible liquid in said bellows limiting contraction of said bellows.

13. A gas lift valve including: a mandrel having a longitudinal flow passage and connectable in a string of tubing to form a section thereof; an outer sleeve mounted on said mandrel providing an annular space extending about and longitudinally of said mandrel to provide an annular flow passage and an annular piston chamber, said mandrel having a discharge port communicating said longitudinal ilow passage of said mandrel with said annular ow passage, said outer sleeve having an inlet port communicating the exterior of said valve with said annular ilow passage, said discharge and inlet ports being longitudinally spaced; an annular valve member slidably mounted in said annular flow passage for limited longitudinal movement between said inlet and discharge ports and relative to said mandrel, said mandrel having annular seat means intermediate said inlet and discharge ports extending radially outwardly into said annular ow passage and providing an annular restriction intermediate the ends of said annular ilow passage, said seat means and said valve member having co-engageable annular seat surfaces for closing said flow passage, said outer sleeve closing one end of said annular passage; an annular piston slidably mounted in said piston chamber and closing the other end of said annular flow passage, said piston being engageable with said annular valve member for moving said valve member in one direction longitudinally of the main mandrel to open position wherein said co-engageable seat surfaces are spaced from one another to provide an annular orice, said discharge port having a .greater effective orifice than said annular orifice whereby when said valve member is in open position and fluid is flowing through said inlet port, said annular passage and said discharge port to said longitudinal flow passage, a pressure differential is created across the valve member tending to move the valve member in the direction of flow from said inlet port to said discharge port, said annular piston having a greater crosssectional area than the cross-sectional area of said annular restriction, said valve having means providing a ow passage communicating said piston chamber with the exterior of said outer sleeve; pilot valve means carried by said mandrel responsive to the pressure within one of said longitudinal ow passage of the mandrel and the exterior of said outer sleeve for opening said passage communicating with said piston chamber to permit flow of uid from the exterior of said outer sleeve into said piston chamber to move said piston in said one direction, said piston having a restricted orice communicating said piston chamber with said annular ow passage; means secured to said mandrel providing a bellows chamber; a bellows connected to said pilot valve means mounted in said bellows chamber, and means biasing said pilot valve means toward closed position, said bellows being exposed to the pressure from the exterior of said valve whereby the pilot valve means is moved to open position when the pressure exteriorly of said valve rises to a predetermined value.

14. The Igas lift valve of claim 13, and a non-compressible liquid in said bellows limiting contraction of said bellows.

15. A gas lift valve including: a mandrel having a longitudinal ow passage and connectable in a string of tubing to -form a section thereof; an outer sleeve mounted on said mandrel providing an annular space extending about and longitudinally of said mandrel to provide an annular flow passage and an annular piston chamber, said mandrel having a discharge port communicating said longitudinal ow passage of said mandrel with said annular flow passage, said outer sleeve having an inlet port communicating the exterior of said valve with said annular flow passage, said discharge and inlet ports being longitudinally spaced, an annular valve member slidably mounted in said annular flow passage between said inlet and outlet ports for limited longitudinal movement between said inlet and discharge ports relative to said mandrel, said mandrel having annular seat means intermediate said ports extending radially outwardly into said annular flow passage and providing an annular restriction intermediate the ends of said annular ilow passage, said seat means and said valve member having annular coengageable seat surfaces, said valve member being movable in said annular passage in the direction of flow from the inlet port to the discharge port to cause said seat surfaces to engage and close said ow passage between said inlet and discharge ports; said outer sleeve closing one end of said annular ow passage; an annular piston slidably mounted in said piston chamber and closing the other end of said annular ow passage, said piston being engageable with said valve member for moving said valve member in one direction longitudinally of the mandrel to open position wherein said co-engageable seat surfaces are spaced from one another to provide an annular orice, said discharge port having a greater effective orifice than said annular orifice whereby when said valve member is in open position and uid is flowing through said inlet port, said annular ow passage and said discharge port to said longitudinal ow passage, a pressure differential is created across the valve member tending to move said valve member in the direction of ilow from said inlet port to said discharge port, said annular piston having a greater cross-sectional area than the cross-sectional area of said annular restriction, said valve having means providing a flow passage communicating said piston chamber with the exterior of said outer sleeve; and pilot valve means carried by said mandrel responsive to the pressure within one of said longitudinal ow passages of the mandrel and the exterior of said outer sleeve for opening said passage communicating said piston chamber with the exterior of said outer sleeve to permit flow of fluid from the exterior of said outer sleeve into said piston chamber to move said piston in said one direction, said piston having a restricted orifice for exhausting iluid from said piston chamber to said annular flow passage. f

16. The gas lift valve of claim 15 wherein said pilot valve means includes a flexible member disposed about said mandrel and between said mandrel and said outer sleeve, said flexible member having an area exposed to said uid pressure from the exterior of said outer sleeve and also having an area exposed to the fluid pressure in said annular flow passage through said restricted orice of said piston, said rst and second areas both being exposed to the pressure of the iluid from the exterior of said outer sleeve when said pilot valve means is moved to open position; a chamber having communication with said ilexible means adaptable to hold a charge of compressed gas whereby the pressure of said charge of compressed gas acting on said flexible member biases said pilot valve means toward closed position.

References Cited by the Examiner UNITED STATES PATENTS 2,631,000 3/53 Lee 251-343 3,045,759 7/62 Garrett 137-510l X 3,077,894 2/ 63 Cummings 137-155 WILLIAM F. ODEA, Primary Examiner.

ISADOR WEIL, Examiner. 

1. A VALVE INCLUDING: A TUBULAR MEMBER HAVING AN INTERNAL FLOW PASSAGE; MEANS ON SAID TUBULAR MEMBER PROVIDING AN ANNULAR FLOW PASSAGE ABOUT SAID TUBULAR MEMBER CLOSED AT ITS ENDS, SAID TUBULAR MEMBER HAVING A DISCHARGE PORT COMMUNICATING SAID INTERNAL FLOW PASSAGE WITH SAID ANNULAR FLOW PASSAGE, SAID MEANS HAVING AN INLET PORT SPACED LONGITUDINALLY OF SAID VALVE FROM SAID DISCHARGE PORT AND COMMUNICATING SAID ANNULAR VALVE SEAT ON WITH THE EXTERIOR OF SAID VALVE; AN ANNULAR VALVE SEAT ON ONE OF SAID TUBULAR MEMBER AND SAID MEANS ON SAID TUBULAR MEMBER IN SAID FLOW PASSAGE BETWEEN SAID PORTS; ANNULAR VALVE MEANS MOVABLY MOUNTED ON SAID TUBULAR MEMBER COATING WITH SAID SEAT FOR CLOSING SAID FLOW PASSAGE BETWEEN SAID INLET AND DISCHARGE PORTS, SAID VALVE MEANS WHEN IN OPEN POSITION BEING DISPOSED BETWEEN SAID INLET AND DISCHARGE PORTS AND MOVABLE TOWARD SAID DISCHARGE PORT TOWARD CLOSED POSITION ENGAGING SAID SEAT, SAID VALVE MEANS WHEN IN OPEN POSITION PROVIDING WITH SAID VALVE SRAT AND WITH ONE OF SAID TUBULAR MEMBER AND SAID MEANS ON SID TUBULAR MEMBER AN ANNULAR ORIFICE IN SAID FLOW PASSAGE ABOUT SAID TUBULAR MEMBER LOCATED BETWEEN SID INLET AND DISCHARGE PORTS, SAID DISCHARGE PORT HAVING A GREATER EFFECTIVE ORIFICE THAN SAID ANNULAR ORIFICE WHEREBY WHEN AID VALVE MEANS IS IN OPEN POSITION AND FLUID IS FLOWING FROM SAID INLET PORT THROUGH SAID ANNULAR FLOW PASASGE AND SAID DISCHARGE PORT TO SAID INTERNAL FLOW PASSAGE A PRESSURE DIFFERENTIAL IS CREATED ACROSS SAID VALVE MEANS TENDING TO MOVE SAID VALVE MEANS TO POSITION CLOSING SAID ANNULAR FLOW PASSAGE; ANNULAR OPERATOR PISTON MEANS IN SAID FLOW PASSAGE BETWEEN SAID DISCHARGE PORT AND THE ADJACENT CLOSED END OF SAID PASSAGE OPERATIVELY ASSOCIATED WITH SAID VALVE MEANS AND EXPOSED AT ONE END TO FLUID PRESSURE IN SAID PASSAGE BETWEEN SAID VALVE SEAT AND SAID DISCHARGE PORT AND AT ITS OPPOSITE END TO FLUID PRESSURE IN SAID PASSAGE BETWEEN SAID PISTON MEANS AND SAID CLOSED END OF SAID PASSAGE; AND CONDUIT AND CONTROL MEAND FOR CONDUCTING FLUID PRESSURE FROMM EXTERIORITY OF SAID VALVE TO SID PASSAGE BETWEEN SAID PISTON AND SAID CLOSED END OF SAID PASSAGE TO ACT ON SAID OPPOSITE END OF SAID PISTON TO MOVE SAID PISTON AND SAID VALVE MEANS ASSOCIATED THEREWITH TO MOVE SAID VALVE MEANS OUT OF ENGAGEMENT WITH SAID SEAT TO OPEN THE ANNULAR PASSAGE FOR FLOW, SAID OPERATOR PISTON MEANS HAVING A GREATER CROSS-SECTIONAL AREA THAN THE EFFECTIVE CROSS-SECTIONAL AREA OF SAID ANNULAR VALVE MEANS. 